CD34+ cell mobilization and upregulation of myocardial cytokines in a rabbit model of myocardial ischemia

Evaluation the effect of testosterone on the number of endothelial progenitor cells and amount of SDF-1α, PDGF, bFGF, and NO

Background:

Recent therapeutic advances in cardiovascular disease, thanks to the discovery of endothelial progenitor cells (EPCs). Stromal cell-derived factor-1α (SDF-1α), platelet-derived growth factor (PDGF), basic fibroblast growth factor (bFGF), and nitric oxide (NO) play a role in migration, homing, and differentiation of EPCs into mature endothelial cells. The incidence of cardiovascular disease is higher in men than in women. This fact suggests the influence of sex hormones on incidence of cardiovascular disease.

Methods:

Twenty-four female wistar rats weighing 160–180 g were randomly divided into four groups (N = 6): 1. sham-treated by sesame oil, 2. ovariectomized (OVX)-treated by sesame oil, 3. OVX-treated by 10 μg/kg/day testosterone, and 4. OVX-treated by 100 μg/kg/day testosterone. After 21 days, the animals were euthanized and blood samples were saved for determination of EPC count and serum levels of SDF-1α, PDGF, bFGF, and NO production.

Results:

High-dose testosterone induced significant increase in EPC count in OVX rats (P < 0.05). Also 100 μg/kg/day testosterone increased serum level of SDF-1α more than OVX-treated by 10 μg/kg/day testosterone (P < 0.05). But 10 μg/kg/day testosterone increased significantly the serum level of PDGF >100 μg/kg/day testosterone-treated group (P < 0.05). The serum level of bFGF in sham-treated by sesame oil was equal with its concentration in OVX-treated by 100 μg/kg/day testosterone. And the serum concentration of NO production in testosterone-treated groups were significantly less than other groups (P < 0.05).

Conclusions:

This study suggests that testosterone might be effective on cardiovascular disease in females by increasing EPC count through SDF-1α and PDGF mechanisms which are some of the vascular healing factors.

Comparing the effect of intestinal bacteria from rabbit, pig, and chicken on inflammatory response in cultured rabbit crypt and villus

Rabbit is susceptible to intestinal infection, which often results in severe inflammatory response. To investigate whether the special community structure of rabbit intestinal bacteria contributes to this susceptibility, we compared the inflammatory responses of isolated rabbit crypt and villus to heat-treated total bacteria in pig, chicken, and rabbit ileal contents. The dominant phylum in pig and chicken ileum was Firmicutes, while Bacteroidetes was dominant in rabbit ileum. The intestinal bacteria from rabbit induced higher expression of toll-like receptor 4 (TLR4) in rabbit crypt and villus (P < 0.05). TLR2 and TLR3 expression was obviously stimulated by chicken and pig intestinal bacteria (P < 0.05) but not by those of rabbit. The ileal bacteria from those three animals all increased the expression of tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6) in crypts and villus (P < 0.05). Chicken and pig ileal bacteria also stimulated the expression of anti-inflammatory factors interferon beta (IFN-β) and IL-10 (P < 0.05), while those of rabbit did not (P > 0.05). In conclusion, a higher abundance of Gram-negative bacteria in rabbit ileum did not lead to more expressive pro-inflammatory cytokines in isolated rabbit crypt and villus, but a higher percentage of Lactobacillus in chicken ileum might result in more expressive anti-inflammatory factors.

Critical assessment of the efficiency of CD34 and CD133 antibodies for enrichment of rabbit hematopoietic stem cells

Rabbits have many hereditary diseases common to humans and are therefore a valuable model for regenerative disease and hematopoietic stem cell (HSC) therapies. Currently, there is no substantial data on the isolation and/or enrichment of rabbit HSCs. This study was initiated to evaluate the efficiency of the commercially available anti-CD34 and anti-CD133 antibodies for the detection and potential enrichment of rabbit HSCs from peripheral blood. PBMCs from rabbit and human blood were labelled with different clones of anti-human CD34 monoclonal antibodies (AC136, 581, and 8G12) and rabbit polyclonal CD34 antibody (pCD34) and anti-human CD133 monoclonal antibodies (AC133 and 293C3). Flow cytometry showed a higher percentage of rabbit CD34⁺ cells labelled by AC136 in comparison to the clone 581 and pCD34 (P < 0.01). A higher percentage of rabbit CD133⁺ cells were also detected by 293C3 compared to the AC133 clone (P < 0.01). Therefore, AC136 clone was used for the indirect immunomagnetic enrichment of rabbit CD34⁺ cells using magnetic-activated cell sorting (MACS). The enrichment of the rabbit CD34⁺ cells after sorting was low in comparison to human samples (2.4% vs. 39.6%). PCR analyses confirmed the efficient enrichment of human CD34⁺ cells and the low expression of CD34 mRNA in rabbit positive fraction. In conclusion, the tested antibodies might be suitable for detection, but not for sorting the rabbit CD34⁺ HSCs and new specific anti-rabbit CD34 antibodies are needed for efficient enrichment of rabbit HSCs. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 2018 © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 34:1278-1289, 2018.

Hypoxia Supports Epicardial Cell Differentiation in Vascular Smooth Muscle Cells through the Activation of the TGFβ Pathway

Epicardium-derived cells (EPDCs) are an important pool of multipotent cardiovascular progenitor cells. Through epithelial-to-mesenchymal-transition (EMT), EPDCs invade the subepicardium and myocardium and further differentiate into several cell types required for coronary vessel formation. We previously showed that epicardial hypoxia inducible factor (HIF) signaling mediates the invasion of vascular precursor cells critical for patterning the coronary vasculature. Here, we examine the regulatory role of hypoxia (1% oxygen) on EPDC differentiation into vascular smooth muscle cells (VSMCs). Results: Hypoxia stimulates EMT and enhances expression of several VSMC markers in mouse epicardial cell cultures. This stimulation is specifically blocked by inhibiting transforming growth factor-beta (TGFβ) receptor I. Further analyses indicated that hypoxia increases the expression level of TGFβ-1 ligand and phosphorylation of TGFβ receptor II, suggesting an indispensable role of the TGFβ pathway in hypoxia-stimulated VSMC differentiation. We further demonstrate that the non-canonical RhoA/Rho kinase (ROCK) pathway acts as the main downstream effector of TGFβ to modulate hypoxia’s effect on VSMC differentiation. Conclusion: Our results reveal a novel role of epicardial HIF in mediating coronary vasculogenesis by promoting their differentiation into VSMCs through noncanonical TGFβ signaling. These data elucidate that patterning of the coronary vasculature is influenced by epicardial hypoxic signals.

Myocardial Ischemia and Mobilization of Circulating Progenitor Cells

Background

The response of progenitor cells (PCs) to transient myocardial ischemia in patients with coronary artery disease remains unknown. We aimed to investigate the PC response to exercise‐induced myocardial ischemia (ExMI) and compare it to flow mismatch during pharmacological stress testing.

Methods and Results

A total of 356 patients with stable coronary artery disease underwent 99mTc‐sestamibi myocardial perfusion imaging during exercise (69%) or pharmacological stress (31%). CD34⁺ and CD34⁺/chemokine (C‐X‐C motif) receptor 4 PCs were enumerated by flow cytometry. Change in PC count was compared between patients with and without myocardial ischemia using linear regression models. Vascular endothelial growth factor and stromal‐derived factor‐1α were quantified. Mean age was 63±9 years; 76% were men. The incidence of ExMI was 31% and 41% during exercise and pharmacological stress testing, respectively. Patients with ExMI had a significant decrease in CD34⁺/chemokine (C‐X‐C motif) receptor 4 (−18%, P=0.01) after stress that was inversely correlated with the magnitude of ischemia (r=−0.19, P=0.003). In contrast, patients without ExMI had an increase in CD34⁺/chemokine (C‐X‐C motif) receptor 4 (14.7%, P=0.02), and those undergoing pharmacological stress had no change. Plasma vascular endothelial growth factor levels increased (15%, P<0.001) in all patients undergoing exercise stress testing regardless of ischemia. However, the change in stromal‐derived factor‐1α level correlated inversely with the change in PC counts in those with ExMI (P=0.03), suggesting a greater decrease in PCs in those with a greater change in stromal‐derived factor‐1α level with exercise.

Conclusions

ExMI is associated with a significant decrease in circulating levels of CD34⁺/chemokine (C‐X‐C motif) receptor 4 PCs, likely attributable, at least in part, to stromal‐derived factor‐1α–mediated homing of PCs to the ischemic myocardium. The physiologic consequences of this uptake of PCs and their therapeutic implications need further investigation.

Intratracheal administration of isosorbide dinitrate improves pulmonary artery pressure and ventricular remodeling in a rat model of heart failure following myocardial infarction

Pulmonary hypertension due to left heart disease is associated with poor outcomes. This study investigated the beneficial effects of isosorbide dinitrate (ISDN) inhalation on pulmonary pressure and ventricular remodeling in a rat model of heart failure (HF) following myocardial infarction (MI). To assess the effect of ISDN on pulmonary pressure, 20 male Sprague-Dawley (SD) rats were randomized to four groups: Normal saline (NS) 1 ml/kg, ISDN 1 mg/kg, NS 3 ml/kg or ISDN 3 mg/kg following coronary ligation. Assessments included pulmonary and systemic artery pressure alterations, lung weight/body weight and plasma nitric oxide (NO) concentration. To assess the effect of ISDN on ventricular remodeling, 30 SD rats were randomized to three groups: Sham surgery, MI-NS (intratracheal NS 3 ml/kg for 13 days following coronary ligation), and MI-ISDN (intratracheal ISDN 3 mg/kg for 13 days following coronary ligation). On day 15, all rats underwent echocardiogram and hemodynamic assessments. The area affected by MI was evaluated using microscopy and vascular endothelial growth factor (VEGF) expression was examined using immunohistochemistry. Plasma epinephrine, norepinephrine and brain natriuretic peptide (BNP) levels were assessed by ELISA. Intratracheal ISDN reduced pulmonary and systematic artery pressure without pulmonary edema when compared with NS. The reduction was associated with increased plasma NO levels. ISDN inhalation for 14 days reduced MI size and alleviated left and right ventricular remodeling following MI. These hemodynamic and morphological improvements were associated with decreased plasma epinephrine, norepinephrine and BNP levels, and an increased VEGF positive area at the border of MI region. In conclusion, intratracheal administration of ISDN was effective in improving ventricular remodeling and cardiac function in a rat model of HF following MI.

Protective effect of Xuebijing injection against acute lung injury induced by left ventricular ischemia/reperfusion in rabbits

Xuebijing (XBJ) is a Chinese herbal preparation. Previous studies have demonstrated that XBJ injection is able to inhibit the uncontrolled release of endogenous inflammatory mediators, attenuate inflammation, and alleviate organ damage. However, there are no relevant reports on the protective effect of XBJ against left ventricular ischemia/reperfusion (I/R)-induced acute lung injury (ALI). Therefore, the aim of the present study was to evaluate the protective effect of XBJ on ALI induced by left ventricular I/R, and provide evidence for the clinical application of XBJ. In the present study, 120 healthy rabbits of mixed gender were randomly assigned to a normal control group, ischemia group, I/R group (I/RG) and XBJ-injection treatment group (TG). In addition, each group was further divided into three subgroups (n=10/subgroup), namely, 30 min pre-ischemia, 30 min post-ischemia and 30 min post-reperfusion subgroups. Blood samples (5 ml) were collected from the jugularis externa and carotis communis of the rabbits at the three time points, and a blood gas analyzer was used to measure the arterial partial pressure of oxygen (PaO₂) and carbon dioxide (PaCO₂). Following sacrifice, the lungs of the rabbits were removed and a bronchoalveolar lavage (BAL) was immediately performed. An enzyme-linked immunosorbent assay was used to measure the expression levels of tumor necrosis factor-α (TNF-α) in the BAL fluid (BALF) and peripheral blood. In addition, the lower lobe of the right lung was removed in order to measure the protein expression levels of intercellular adhesion molecule-1 (ICAM-1) and TNF-α. The results demonstrated that in the rabbits of the TG PaO₂ was increased, PaCO₂ was decreased, the lung tissue congestion edema was attenuated, the expression levels of TNF-α in the peripheral blood and BALF were reduced and the protein expression levels of ICAM-1 and TNF-α in the lung tissue samples were decreased, as compared with those in the I/RG rabbits. These results suggest that XBJ may protect against left ventricular I/R-induced ALI by regulating the expression of the inflammatory mediators TNF-α and ICAM-1.

Avemar and Echinacea extracts enhance mobilization and homing of CD34(+) stem cells in rats with acute myocardial infarction

Introduction

Activation of endogenous stem cell mobilization can contribute to myocardial regeneration after ischemic injury. This study aimed to evaluate the possible role of Avemar or Echinacea extracts in inducing mobilization and homing of CD34⁺ stem cells in relation to the inflammatory and hematopoietic cytokines in rats suffering from acute myocardial infarction (AMI).

Methods

AMI was developed by two consecutive subcutaneous injections of isoprenaline (85 mg/kg). AMI rats were either post-treated or pre- and post-treated daily with oral doses of Avemar (121 mg/kg) or Echinacea (130 mg/kg). In whole blood, the number of CD34⁺ cells was measured by flow cytometry and their homing to the myocardium was immunohistochemically assessed. Serum creatine kinase, vascular endothelial growth factor, interleukin-8 and granulocyte macrophage colony stimulating factor were determined on days 1, 7 and 14 after AMI. Sections of the myocardium were histopathologically assessed.

Results

Rats pre- and post-treated with Avemar or Echinacea exhibited substantial increases in the number of circulating CD34⁺ cells, peaking on the first day after AMI to approximately 13-fold and 15-fold, respectively, with a decline in their level on day 7 followed by a significant increase on day 14 compared to their corresponding AMI levels. Only post-treatment with Echinacea caused a time-dependent increase in circulating CD34⁺ cells on days 7 and 14. Such increases in circulating CD34⁺ cells were accompanied by increased homing to myocardial tissue 14 days after AMI. Interestingly, pre- and post-treatment with Avemar or Echinacea substantially increased serum creatine kinase on day 1, normalized its activity on day 7 and, on continued treatment, only Echinacea markedly increased its activity on day 14 compared to the corresponding AMI values. Moreover, both treatments modified differently the elevated serum vascular endothelial growth factor and the lowered granulocyte macrophage colony stimulating factor levels of the AMI group but did not affect the level of interleukin-8. These results were supported histopathologically by reduced inflammatory reactions and enhanced neovascularization.

Conclusion

Avemar and Echinacea extracts can effectively induce mobilization and homing of CD34⁺ stem cells to the myocardial tissue and thus may help in stem cell-based regeneration of the infarcted myocardium.